1. Field of Invention
The invention relates to a technical field of electro-optical devices and electronic apparatus. Particularly, the invention relates to an electro-optical device capable of so-called active matrix addressing by providing a thin film transistor (TFT) on one of two substrates having an electro-optical substance, such as a liquid crystal, interposed between the substrates, and an electronic apparatus having such an electro-optical device.
2. Description of Related Art
Conventional electro-optical devices capable of so-called active matrix addressing can include pixel electrodes arranged as a matrix, TFTs connected to the electrodes, and scanning lines and data lines aligned parallel to column and row directions, respectively, of the matrix, whereby operation of the TFT is controlled by supplying scanning signals to the TFT via the scanning lines, and image signals are supplied to the TFTs and pixel electrodes via the data lines. The need for a small size electro-optical device capable of displaying improved quality of images has been has increased in recent years.
Although various problems should be solved for satisfying such requirement, among all of them, it is important to overcome the problems concerning incidence of light to the TFT provided at each pixel, particularly, to a channel region in the semiconductor layer. This is because a leak photocurrent can occur by photo-excitation caused by irradiation of light onto the channel region, and images on the display are flickered due to change of characteristics of the TFT. In particular, when the electro-optical device capable of active matrix addressing is used as a light bulb for a liquid crystal projector, shielding of the incident light to the channel region of the TFT and peripheral region thereof becomes more important since the intensity of the incident light to the light bulb is high.
Accordingly, conventional electro-optical devices have been constructed so that the light is blocked from arriving at the channel region and the peripheral regions thereof by providing a light shielding layer for restricting an opening region of each pixel on a counter substrate facing a TFT array substrate on which the TFT is mounted with interposition of an electro-optical substance such as a liquid crystal between the two substrates. Alternatively, the electro-optical device has been constructed so that data lines made of a metal film, such as an Al (aluminum) film, that runs on the TFT is used as the light shielding layer on the TFT array substrate. Such construction prevents the light from impinging into the TFT and its channel region of the electro-optical device, that is, the leak photocurrent is prevented from occurring.
However, the light shielding technology as described above involves the following problems. According to the technology for forming the light shielding layer on the counter substrate or above the TFT array substrate, the light shielding layer is considerably separated from the channel region in a three dimensional construction consisted of, for example, a liquid crystal layer, electrodes, interlayer insulating layers and others, thus the light impinging into the space between the light shielding layer and the channel region from an inclined direction is not sufficiently shielded. In particular, in the small size electro-optical device, using a light bulb for the projector, the light flux of the incident light from a light source is converged with a lens, and contains considerable inclined components of incident light that cannot be disregarded (about 10% of the light component, which is 10° to 15° aslant from the direction perpendicular to the substrate). Accordingly, insufficient shielding of such inclined incident light arises as a practical problem.